A-B 1756-ENBT Module Rockwell ControlLogix Communication Control

Common Industrial Protocol 

(CIP) CIP™ is a messaging protocol for devices in industrial automation control systems. 

CIP is the application layer for the EtherNet/IP network. 

This protocol implements a relative path to send a message from the producing modules in a system to the consuming modules. 

CIP uses the Producer/Consumer networking model instead of a source/ destination (Primary/Secondary) model. 

The Producer/Consumer model reduces network traffic and increases speed of transmission. 

In traditional I/O systems, controllers poll input modules to obtain their input status. 

In the CIP system, digital input modules are not polled by a controller. 

Instead, they produce their data either upon a change of state (COS) or at a requested packet interval (RPI).

The frequency of update depends upon the options that are chosen during configuration and where on the network the input module resides. 

The input module, therefore, is a producer of input data and the controller is a consumer of the data. 

The controller can also produce data for other controllers to consume.

The produced and consumed data is accessible by multiple controllers over the Logix backplane and over the EtherNet/IP network. 

This data exchange conforms to the Producer/Consumer model.

These faults and warnings can be cleared with a clear faults command. 

You may have to perform a reset after power-up, or perform multiple resets.

Local DH+ Messaging Devices use local DH+ messaging to communicate between devices on the same physical link.

A device that uses local DH+ messaging must: 

• generate local DH+ packets. 

• support local DH+ protocol. 

• send and receive messages. 

A local DH+ message sent on a DH+ network has only enough address information to get the message 

to a target node on the same DH+ network. 

The example in the following figure shows a PLC-5 controller sending a message to port A on the 1756-DHRIO and 1756-DHRIOXT modules. 

Because the controller slot for port A is configured to “0”, the message is forwarded to the ControlLogix controller in slot 0.

Receiving Local DH+ Messages on DH+ Because a local DH+ message 

has only enough address information to get the message to a target node on the same DH+ network, 

the 1756-DHRIO and 1756-DHRIOXT modules that receive this message cannot identify where to send the message. 

The 1756-DHRIO and 1756-DHRIOXT modules use the Controller Slot configuration parameter to send the message to the local controller. 

You must use RSLinx software to configure the controller slot. 

Some messages, called PCCC commands, are not sent to the controller slot. 

In this case, the 1756-DHRIO and 1756-DHRIOXT modules generate a response to the message. 

For a complete list of these messages, see Appendix B. 

Local DH+ messaging does not require a populated routing table. 

Local DH+ messaging does require a default (that is a properly emptied) or an applied (that is a properly populated and saved) routing table, 

and a default or applied controller slot for each channel configured for DH+. 

A modern control system is more than its name implies. It delivers the fast system performance, 

high capacity and optimized productivity that you need from a control system today.